Martello Castle Background Information

Summary information on the Lake Pontchartrain Basin and its watershed area is a compilation of U.S. Army Corps of Engineer and Task force reports, Lake Pontchartrain Basin Foundation studies, reports, articles, website and CD-rom, Open File government documents, Internet accessible data, articles related to Lake Pontchartrain, and interviews with experts on wetland loss and change. Only direct quotes or facts are cited. General information from multiple sources and data from Internet websites are not cited. References consulted are located at the end of this summary.

The Lake Pontchartrain Basin Foundation

The Lake Pontchartrain Basin Foundation, a membership-based citizen’s organization, is the public’s independent voice dedicated to restoring and preserving the Lake Pontchartrain Basin. The foundation was established in 1989 as a citizen's group to organize help with the restoration efforts in the Basin. The Foundation works in partnership with all segments of the community to reclaim the waters and habitats for this and future generations.

The mission and goals of the Lake Pontchartrain Basin Foundation are the same: to restore and preserve the Lake Pontchartrain Basin through coordination of restoration activities, education, advocacy, monitoring of the regulatory process, and citizen action. The Foundation’s goals are to promote stewardship, to protect the estuary and its habitats, and to restore the Basin to a safe and clean environment.

The Foundation is making progress with many major accomplishments (Table 1). As a result of the Lake Pontchartrain Basin Foundation’s advocacy, shell dredging has been stopped, seagrasses are beginning to reestablish their colonies, local fishermen are seeing population increases in fisheries, and pollution levels in Lake Pontchartrain and Basin rivers have decreased. The Foundation plans several future projects including assisting Orleans and Jefferson Parishes with programs to reduce sewage pollution along the southshore of Lake Pontchartrain, developing new educational resources and environmental programs, and initiating citizen involvement projects to restore habitats on both the north and south shores of Lake Pontchartrain. Salt water intrusion and erosion from the Mississippi River Gulf Outlet (MRGO) remain a concern for the Basin. The Foundation is developing a long-term program to address the multiple issues within the Lake Pontchartrain Basin. Also, the Foundations plans to develop a comprehensive wastewater management plan for Tangipahoa Parish, advanced treatment systems for individual home sewage systems, sewage disposal programs for camps in the Basin, and programs to eliminate pollution from boat repair yards.

Developed Programs

Comprehensive Management Plan

Coordinated effort for cleanup of Pontchartrain Basin

Wastewater management plan for St. Tammany Parish

Based on reversal of wetland damage to St. Bernard Parish wetlands

Environmental Education Programs

Classroom presentations; Field programs; Canal/River Watch; Summer Camps; Education Guide; Teacher Workshops; "Pontchartrain Stories" Video; Grants to Schools; Educational Materials; Research

Cost-share program

Assist farmers with construction of animal waste retention lagoons

Restoration of Lake Pontchartrain Basin

Initiated Shell Dredging Ban

Challenged water quality permits

Establishment of Big Branch Wildlife Refuge in St. Tammany Parish

Constructed a septic waste disposal facility for north shore parishes.

Prevented expansion of oil and gas operations with pollution records in the Lake.

Sampling of more than 40 Lake water quality sites monthly.

Replanting of sea grasses to replace losses due to past poor water quality, hurricanes and shoreline erosion.

Provide Technical Advice, Help, Coordination, and Monitoring

Technical advice to over 100 northshore wastewater treatment plants.

Helped New Orleans develop long range plans to correct sewage infiltration into the Lake.

Helped Jefferson Parish reroute storm water discharges away from the Lake.

Hosted eight "Back to the Beach" Lake awareness festivals.

Coordinate efforts of thousands of volunteers that contribute tens of thousands of hours to help Save Our Lake.

Continuously watch over the Basin's waters and habitats 365 days a year.

Table 1: Selective list of Lake Pontchartrain Basin Foundation’s accomplishments.

Lake Pontchartrain Basin

The Lake Pontchartrain Basin is in southeastern Louisiana (Local Map) and is just one part of a vast ecological system that includes three large lakes, Maurepas, Pontchartrain, and Borgne, which cover 55 percent of the basin. A land bridge of cypress swamp and fresh/intermediate marsh separate Lakes Maurepas and Pontchartrain. A peninsula of brackish marsh separates Lake Pontchartrain from Lake Borgne. The Lake Pontchartrain watershed is extensive and comprises many diverse habitats from upland evergreen forest to seagrass meadows. Water moves across fields and through forests as it finds its way to small streams in the forested hills north of the lake. This same water joins large rivers and bayous as it flows toward the lakes. One common factor uniting the entire watershed is that all of its water eventually arrives in a wetland for final filtering and purification before it empties into the Gulf of Mexico.

The basin comprises over 4,700 square miles of land in sixteen Louisiana parishes and four counties in Mississippi. All of these lands drain into surrounding rivers and bayous, which empty into Pontchartrain and its connecting sister lakes, Maurepas and Borgne. Pontchartrain also exchanges water with the Gulf of Mexico through The Rigolets and Chef Menteur Pass. This connection of the upper Basin’s fresh water with the salt water of the Gulf makes Lakes Pontchartrain, Maurepas, Borgne one of the largest estuarine systems in the nation (Regional Map). The Basin is known for its slow flowing rivers and bayous, tranquil swamps, and lush hardwood forests. It provides essential habitat for species of fish, birds, mammals, reptiles, and plants. The wetlands and marshes surrounding the Basin’s waters provide a beautiful setting and are the heart of the region’s commercial and recreational fisheries.

The Lake Pontchartrain Basin is a unique ecosystem for the Gulf Coast exhibiting great biodiversity and economic potential.

The Basin is home to 1.5 million people, with more than one quarter of Louisiana’s population residing in parishes surrounding the Lake. Over the last 150 years the urban growth of New Orleans and the northshore communities and the exploitation of natural resources have severely altered the environmental quality of the Pontchartrain Basin.

Local Map: Lake Pontchartrain watershed: 4,700 square miles in southeast Louisiana

Regional map: Regional location of Lake Pontchartrain Basin

Geologic Formation of the Delta

The Pontchartrain Basin is the largest marginal deltaic basin in North America measuring about 200 km along dip and 75 km along strike. The basin is bounded by incised Pleistocene terraces and small bayhead deltas to the north, the Mississippi River delta plain to the south/southwest, and relic Pine Island barrier shoreline to the south/southeast.

Radiocarbon dates for the Pontchartrain Basin shows a complex history of sea level withdrawal, rise, and stillstand followed by barrier shoreline development and deltaic enclosure. The Pontchartrain region was dissected by a series of entrenched river valleys during the Late Wisconsin low stand. Sea level rose during deglaciation, submerging this landscape and depositing a blanket of transgressive nearshore deposits. The Gulf of Mexico shoreline was eroding into the Pleistocene terraces and the formation of a barrier shoreline trend was initiated. The large recurved spit and island complex was built.

Lake Pontchartrain overlies a geologic region that is in a transitional position between two geologic provinces: the Lower Cretaceous margin and the Tertiary basin.

The Lake Pontchartrain Basin began forming about 5,000 years ago when the North American glacier melts caused the Mississippi River to swell and shift to the east. The river deposited sediments into the Gulf of Mexico creating a broad delta, which would later become Orleans, St. Bernard, and Plaquemines parishes (Delta Map). The delta grew slowly eastward over 2,000 years and eventually separated a large body of water from the gulf.

Lake Pontchartrain was formed when the St. Bernard Delta of the Mississippi buried the Pine Island beach completely, covering most of the area and extending out to the Chandeleur Islands. A constricted opening was left about where The Rigolets now exists. Lake Borgne and the eastern part of Mississippi Sound were formed as the St. Bernard Delta was abandoned and began to deteriorate through subsidence and erosion. This resulted in the cut trough of a second opening, Chef Menteur Pass. Because if this, Lake Pontchartrain is a modified bar-built estuary and open water embayment with a surface area of 629 square miles.

Vegetation

About 2000 to 3000 years ago, the Basin began to fill with prodelta, delta front, and crevasse deposits. Cypress swamp and fresh water marshes formed in the upper basin and intermediate to saline marshes formed in the lower Basin. The dominant vegetation in the forested wetlands are cypress and tupelo, willow, and water oak. Scrub-shrub wetlands are characterized by wax myrtle, cypress, iva, bacharries, sable palmetto, red maple, and willow. Salt marshes are dominated by oyster grass (Spartina alterniflora) and saltmeadows are dominated by wiregrass (Spartina patens).

Two dominant types of marsh are found with the Basin: fresh marsh and brackish marsh. Fresh marsh has a one foot thick, dense, live root mat, while the brackish marsh occupies a complex transitional zone between fresh and saline areas with a thin layer of live roots and organic muck (up to eight inches).

Specific Environmental Concerns within the Lake Pontchartrain Basin

Many environmental problems have arisen in the area due to human intervention. Human activities in the Basin have resulted in loss or degradation of important essential habitats. Commercial and residential upland development and construction impact on water quality of the basin. Two damaging activities to wetland habitats are dredging and filling. Water quality problems escalate with increased development around the lake shore, which affects the Basin’s diverse habitats. Loss of wetlands and other critical habitats are due to pollution, hydrological alterations, and development pressures. Non-Point Source Pollution (NPSP) is the major cause of water pollution in the Lake Pontchartrain Basin. Urban storm water runoff, sewage overflow, and agricultural runoff carry various pollutants along as they flow into lakes, streams, and rivers within the Basin. NPS Pollution is difficult to identify and prevent .because everybody generates some form of NPSP. The Lake's southern shore was once a popular place to swim, fish, and picnic, but due to the pollution problems the area has been closed since the 1960s. Regular pollution is not the only thing that has caused areas of the lake to close; the northern shore was closed to the public because of farm and agricultural runoff.

Erosion

Most of Louisiana’s coastal marshes are subsiding or sinking. Subsidence coupled with sea-level rise results in erosion. Nearly all the shoreline of both Lakes Maurepas and Pontchartrain is eroding, typically at a rate of 5 to 10 feet per year, with variation in erosion rates due to shoreline configuration and sediment types. Storms are the principal force for this erosion. An exception to this is the Mississippi Rive Gulf Outlet (MRGO), where the main source of erosion is wave action — a direct result of ship and boat wakes within the channel.

Saltwater intrusion, too, plays an important role in exacerbating problems within Lake Pontchartrain. The most dramatic effect of salt water intrusion is in proximity to the MRGO navigational ship channel, oil and gas canals, levee extraction canals, and drainage ditches. These human alterations cut through the fresh and brackish marshes and forest wetlands of lower St. Bernard Parish, and have been major contributors for existing and continued subsidence and erosion problems. Several solutions for solving erosion and salt water intrusion include filling of existing pipeline canals, and building of rock dikes near Martello Castle in Lake Borgne and between Lakes Maurepas and Pontchartrain.

Mississippi River Gulf Outlet (MRGO)

The Mississippi River Gulf Outlet (MRGO) is located in the southeastern portion of Louisiana and connects the Gulf of Mexico to New Orleans. It is a deep draft seaway channel that extends for approximately 76 miles east and southeast into Breton Sound. The construction of the channel was finished in 1968. The original dimensions were 36 feet deep, 500 feet wide at the bottom, and 650 feet wide at the top. Total construction cost for The U. S. Corps of Engineers project was almost one billion dollars.

Purpose

The purpose of the channel was to shorten the distance for ships from the eastern shipping lanes of the Gulf of Mexico to the Port of New Orleans by about 40 miles. Although the gulf outlet was intended as an economic enhancement for the region, the channel has not lived up to its predicted expectations. The US Government spends over seven to eight million dollars a year just on maintenance and upkeep alone. Opponents of MRGO channel suggest that on average, two ships a day actually use the channel--about 700 a year including recreational and commercial fishing boats, crew boats, supply boats, and deep draft ships. (On the day that the WETMAAP Development Team visited the Martello Castle site in July 1998, six container vessels used the channel.) The result is that the government spends about $10,000 for every ship that uses MRGO. The building and the upkeep of the channel support more than 7,000 jobs. The City of New Orleans has benefitted from the channel by receiving an annual revenue of over $1 billion.

Environmental Effects on the Lake Pontchartrain Basin caused by the MRGO Channel

St. Bernard’s Parish has experienced significant land loss due to the MRGO. Large areas of marsh were converted to open water and disposal areas. Wave-action from vessel traffic continues to erode the marsh along the east bank of the channel, while saltwater intrusion causes land loss and conversion of fresh marsh and swamp to salt marsh.

Before the dredging of the MRGO, freshwater entered adjacent marshes from the area’s lakes, rivers, bayous, and rainfall. This freshwater slowly migrated through Lakes Maurepas, Pontchartrain, and Borgne to wetlands of St. Bernard and Plaquemines parishes, which maintained the historic salinity in these areas. Thousands of acres of cypress tress were destroyed when fresh water swamps and marshes became brackish resulting in "ghost forests."

The MRGO caused an unforseen environmental effect of rapid erosion. More than 4,000 acres of surrounding marshlands have been eroded. A strip of land between Lake Borgne and the channel (Martello Castle area) is narrowing every day and is close to being breached. If this breach occurs, the marshlands along this strip of land will be converted to open water and the surrounding marshlands will be exposed to higher levels of salinity. The La Loutre Ridge acted as a natural tidal barrier from the Gulf's salty waters. With the construction of the channel, this ridge was cut in two, which left a clear path for the saltwater to enter the marshlands.

A major cause of the erosion is the boats and ships that are using the Gulf Outlet channel. There are no wake zones or speed limits in the channel. Consequently, the waves produced are causing massive erosion. If ship speeds were limited, the rate of erosion could be greatly reduced. The original channel was 650 feet wide, but because of severe erosion, the MRGO is as wide as 2,000 feet at some places. Increased tidal exchanges and increased storm surges result in tremendous losses of wetland.

The opening of Louisiana’s coastal marsh to commerce resulted in damage to coastal wetlands and interior marshes. The cutting of the MRGO channel allowed salt water to reach interior marshes displacing fresh water with saltier water, which continues to affect freshwater and brackish water vegetation.

Habitat Change

Severe saltwater intrusion threatens the plant and wildlife in the area. Intrusion of salt water from the channel into fresh water marshes causes destruction of vegetation, increases erosion, salinities in historic oyster beds to change, and the oyster drill predator to became more widespread The distribution and diversity of wildlife dependent on fresh water and marshlands have become threatened due to the habitat reduction in the area. Freshwater fish and fur-bearing animals are forced to migrate and the saltwater wedge fluctuates over time. There are still some aquatic creatures that call the salty marshes home. Red drum, speckled trout, shrimp, oysters, and blue crabs all have valuable nurseries in the salt marsh.

Human activities in the Basin also have resulted in loss or degradation of important essential habitats. Commercial and residential upland development and construction impact on water quality of the basin. Two damaging activities to wetland habitats are dredging and filling. Water quality problems escalate with increased development around the lake shore, which affects the Basin’s diverse habitats.

Vulnerability

Future natural hazards may have greater destructive potential now than in the past. The area surrounding the channel is more vulnerable to hurricanes and floods. Wetlands act as natural buffers and are a primary defense against hurricanes. Marshes that once acted as a buffer zone for New Orleans and other populated areas have been replaced by the MRGO and open water. Issues concerning the MRGO extend beyond St. Bernard Parish affecting the state of Louisiana and the nation.

Controversy

MRGO could be considered an economic blessing to the shipping industry, but it negatively has impacted the ecological systems of the Lake Pontchartrain Basin. The U.S. Army Corps of Engineers recognizes that the MRGO channel resulted in two major problems for the Basin: 1) erosion, primarily caused by wave action, and 2) introduction of salt into the Pontchartrain Basin. The Corps has increased its efforts to re-create some of the marshlands that have eroded through dredge, spoil, deposition, and to provide stabilization of the channel’s banks to minimize future erosion through the use of rip-rap.

The Corps spends $7 to $8 million a year to maintain the MRGO. The Federal government spends one-fourth to one-third of $40 million a year of the Coastal Wetlands Planning, Protection, and Restoration Act (CWPPRA) funds on wetland restoration projects within the Basin in an effort to correct problems associated with wetland loss.

What is the controversy? As a result of numerous efforts, the Corps is attempting to maintain the channel and minimize future impact. Other Federal and State of Louisiana programs are in the process of establishing restoration projects to, in a small measure, help areas revert to previous habitat and water conditions such as the Caernarvon Water Diversion, Fritchie Marsh restoration, and Big Branch National Wildlife Refuge. While at the same time, several environmental groups advocate the closing of the MRGO channel as a means of preventing further damage in an effort to restore the Pontchartrain Basin.

Proposed Solutions

Many groups agree that closing the Gulf Outlet is a good start for slowing down some of the environmental destruction to the Pontchartrain Basin. Rebuilding the natural deltaic and beach the ridges that were cut through will help to maintain the separation of saltwater from freshwater. If closure of the MRGO is not possible, then establishing wake zones and speed limits along the channel would abate shoreline erosion by reducing wave action and lessen saltwater intrusion. Installing a control gate at the south end of the outlet might reduce salinity levels, but would be expensive to build and maintain.

Local Map: The Lake Pontchartrain Basin Watershed Area of Louisiana